In mobile equipment networks, locating user equipments (UEs) can provide valuable additional benefits to users and opportunities for additional or improved services. Typical mobile equipment networks provide wireless access to various communications services for UEs, such as voice, video, data, messaging, content broadcast, VoIP, etc. Wireless networks types can include Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), High Speed Packet Access (HSPA), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Multi-Carrier Code Division Multiple Access (MC-CDMA), Single-Carrier Code Division Multiple Access (SC-CDMA), Orthogonal frequency division multiple access (OFDMA), Single-carrier FDMA (SC-FDMA), etc.
Locating UEs in a wireless network can facilitate providing location-centric services or information in relation to the UE, such as E911 services, mapping services, or traffic information services, among many others. Additionally, UE location information can be employed to improve network performance, to troubleshoot networks, by law enforcement, to aggregate valuable demographic information, or nearly a limitless number of other uses. Such additional usage of UE location data can proactively include removal or obfuscation of identifying information at various levels to address privacy concerns.
Traditional methods of determining UE locations include measuring the timing delay of the signals transmitted between the wireless base station and the wireless handset and applying various location services or methods, including, but not limited to, cell global identity and timing advance (CGI+TA), CGI and round trip time (CGI+RTT), time of arrival (TOA), or other custom methods. Network timing delays include site timing delay in the wireless signal path among radio component(s) at the wireless base station and a sector antenna. Network timing delays further include delays that can arise from various mismatches (e.g., impedance mismatch) among electronic elements and components, stray capacitances and inductances, length of the antenna(s) cable(s) in base station(s); tower height of base station, signal path scattering, or “signal bounces,” such as multipath or strong reflections, and the like. Propagation delay between a UE and a NodeB is conventionally assumed to be negligible with respect to timing delay. However, depending on the architecture of the serving base station and covered sector antenna(s) signal propagation delay can be substantive, particularly in distributed antenna systems and low-power wireless radio cells and cause significant error in UE location determinations for traditional methods.
It is becoming more common to try to determine propagation delay with improved accuracy so as to improve UE location calculations. Conventional UE location techniques include, but are not limited to, Cell ID (CID) wherein errors of multiple km are expected, Enhanced CID (ECID) which includes mobile timing advance and allows location of the mobile within an arc some distance from the base site and errors can still be multiple km, RF signal strength (RSSI) reported by the UE often having errors of >1 km due to RSSI variation, Round Trip Time (RTT) for multilateration from three or more base sites with errors often >1 km, Uplink Time Difference of Arrival (UTDOA) using specialized receivers on three or more base stations to measure the propagation time difference between the mobile and sites, or Assisted GPS (AGPS) using a GPS receiver in a UE to compute its own location to <10 m where satellite coverage is accessible (which can be <70% of the time.)